JP2007312958A - Ultrasonic diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic system displaying an elastic image suitable for diagnosing. <P>SOLUTION: The ultrasonic diagnostic device is equipped with an ultrasonic probe 12, a tomographic image constituting means 20 generating tomographic images from RF signal frame data of the sectional layer section of a subject via the ultrasonic probe 12, an elastic information calculating means 32 obtaining the distortion or elasticity of the tissue in the sectional layer section from the RF signal frame data, an elastic image constituting means 34 generating the elastic image in the sectional layer section from the distortion or elasticity obtained by the elastic information calculating means 32, and a display means 26 displaying the tomographic image and/or the elastic image. The device is further equipped with an error evaluating section 40 evaluating the error of the elastic image and specifying the error area using brightness information of the elastic image or the tomographic image and an image control means 44 displaying the error information in the elastic image or eliminating the elastic image relating to the error area relating to the area specified by the error evaluating section 40. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus for displaying a tomographic image and an elastic image showing the hardness or softness of a living tissue for an imaging target region in a subject using ultrasonic waves.

  The ultrasonic diagnostic apparatus transmits an ultrasonic wave to the inside of the subject using an ultrasonic probe, receives an ultrasonic reflected echo signal corresponding to the structure of the living tissue from the inside of the subject, for example, an ultrasonic tomographic image or the like A tomographic image is constructed and displayed for diagnosis.

  In recent years, an ultrasonic probe is used to measure an ultrasonic reception signal with an ultrasonic probe by a manual or mechanical method, and a living body generated by compression based on frame data of two ultrasonic reception signals with different measurement times. For example, Patent Document 1) discloses that a displacement of each part is obtained and an elastic image representing the elasticity of a living tissue is generated based on the displacement data.

Also, the displacement frame data of the elastic image is used to determine the variation in local displacement, and measurement points with large variations are evaluated as having low display value, and measurement points with small variation are evaluated as having high display value. And displaying an elastic image. (For example, Patent Document 2)
JP 2000-60853 A International Publication No. WO04 / 105615

However, in the above-mentioned known document, the variation in the elastic image is obtained and evaluated, and the evaluation is not performed in conformity with the tissue region in the elastic image region and the measurement conditions. Therefore, when the elastic image is acquired, if a measurement condition such as compression is inappropriate, an incorrect strain is acquired, for example, displayed in blue, and the tissue is recognized as being hard. Further, even in a region where no cancer occurs in the prostate tissue, it is displayed in, for example, blue because of the characteristics of the tissue, and the tissue is recognized as being hard. For this reason, in the blue area (tissue), information indicating that cancer is suspected is given to the examiner, which may lead to misdiagnosis.
Therefore, an object of the present invention is to display an elastic image suitable for diagnosis.

  In order to solve the above problems, the present invention is configured as follows. An ultrasonic probe, tomographic image constructing means for generating a tomographic image based on RF signal frame data of a tomographic region of the subject via the ultrasonic probe, and the tomographic image based on the RF signal frame data Elastic information calculating means for obtaining strain or elastic modulus of tissue in the site; elastic image constructing means for generating an elastic image in the tomographic site based on the strain or elastic modulus obtained by the elastic information calculating means; And / or an error evaluation for evaluating an error of the elastic image and designating an error region using luminance information of the elastic image and the tomographic image in an ultrasonic diagnostic apparatus comprising a display unit for displaying the elastic image And an image for displaying error information on the elastic image or deleting the elastic image related to the error area for the area specified by the error evaluation unit. Image control means.

  As described above, according to the present invention, an elastic image suitable for diagnosis can be displayed, and image information that can lead to misdiagnosis can be prevented from being given to the examiner.

An ultrasonic probe and an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus to which the present invention is applied.
As shown in FIG. 1, the ultrasound diagnostic apparatus 1 includes an ultrasound probe 12 that is used in contact with the subject 10 and a time interval between the subject 10 via the ultrasound probe 12. A transmitter 14 that repeatedly transmits ultrasonic waves, a receiver 16 that receives time-series reflected echo signals generated from the subject 10, an ultrasonic transmission / reception controller 17 that controls the transmitter 14 and the receiver 16, and a reception A phasing addition unit 18 for phasing and adding the reflected echo received by the unit 16 is provided.

  Further, based on the RF signal frame data from the phasing addition unit 18, the tomographic image forming unit 20 that forms a tomographic image of the subject, for example, a black and white tomographic image, and the output signal of the tomographic image forming unit 20 are output from the image display 26. A black-and-white scan converter 22 is provided for conversion to suit the display.

  The RF signal frame data output from the phasing addition unit 18 is stored, the RF frame data selection unit 28 that selects at least two pieces of frame data, and the displacement measurement unit that measures the displacement of the biological tissue of the subject 10 An elastic information calculation unit 32 that obtains strain or elastic modulus from the displacement information measured by the displacement measuring unit 30; and an elastic image configuration unit 34 that forms a color elastic image from the strain or elastic modulus calculated by the elastic information calculation unit 32; And a color scan converter 36 for converting the output signal of the elastic image construction unit 34 so as to match the display of the image display 26. Then, a black and white tomographic image and a color elasticity image are superposed or displayed in parallel, and a switching addition unit 24 that performs switching, and an image display 26 that displays the synthesized composite image are provided.

  Also, error evaluation for evaluating the error of the elastic image from the output information of the RF signal frame data selecting unit 28, the displacement measuring unit 30, the elastic information calculating unit 32, the elastic image forming unit 34, the tomographic image forming unit 20, or the black and white scan converter 22. A unit 40, an error evaluating unit 40, an image control unit 44 for controlling the elastic image forming unit 34 and the color scan converter 36, and an interface unit 42 for giving an instruction to the image control unit 44.

  Here, the ultrasonic diagnostic apparatus 1 will be described in detail. The ultrasonic probe 12 is formed by arranging a plurality of transducers, and has a function of transmitting and receiving ultrasonic waves to and from the subject 10 via the transducers. The transmission unit 14 generates a transmission pulse for generating an ultrasonic wave by driving the ultrasonic probe 12, and has a function of setting a convergence point of the transmitted ultrasonic wave to a certain depth. Yes. The receiving unit 16 amplifies the reflected echo signal received by the ultrasonic probe 12 with a predetermined gain to generate an RF signal, that is, a received signal. The phasing adder 18 receives the RF signal amplified by the receiver 16 and performs phase control to generate a received ultrasonic beam signal.

  The tomographic image construction unit 20 receives the received beam signal from the phasing addition unit 18 and performs signal processing such as gain correction, log compression, detection, contour enhancement, filter processing, etc., to obtain tomographic image data. The monochrome scan converter 22 includes an A / D converter that converts the tomographic image data from the tomographic image construction unit 20 into a digital signal, a frame memory that stores a plurality of converted tomographic image data in time series, and a control It is configured to include a controller. This monochrome scan converter 22 acquires tomographic frame data in the subject stored in the frame memory as one image, and reads the acquired tomographic frame data in synchronization with the television.

  The RF frame data selection unit 28 stores a plurality of RF signal frame data from the phasing addition unit 18, and selects one set, that is, two RF signal frame data from the stored RF signal frame data group. For example, the RF signal frame data generated from the phasing adder 16 based on the time series, that is, the frame rate of the image, is sequentially stored in the RF frame data selector 28, and the stored RF signal frame data (N) is stored in the first At the same time, one RF signal frame data (X) is selected from among RF signal frame data groups (N−1, N−2, N−3... N−M) stored in the past in time. select. Here, N, M, and X are index numbers assigned to the RF signal frame data, and are natural numbers.

  Then, the displacement measuring unit 30 performs one-dimensional or two-dimensional correlation processing from the selected set of data, that is, the RF signal frame data (N) and the RF signal frame data (X), and corresponds to each point of the tomographic image. A one-dimensional or two-dimensional displacement distribution related to the displacement and movement vector in the living tissue, that is, the direction and magnitude of the displacement is obtained. Here, a block matching method is used to detect the movement vector. The block matching method divides an image into blocks consisting of N × N pixels, for example, focuses on the block in the region of interest, searches the previous frame for the block that most closely matches the block of interest, and refers to this Then, predictive encoding, that is, processing for determining the sample value by the difference is performed.

  The elasticity information calculation unit 32 calculates the strain value or elasticity of the living tissue corresponding to each point on the tomographic image from the measurement value output from the displacement measurement unit 30, for example, the movement vector and the pressure value output from the pressure measurement unit 46. The modulus is calculated, and an elastic image signal, that is, elastic frame data is generated based on the strain and elastic modulus.

  At this time, the strain data is calculated by spatially differentiating the movement amount of the living tissue, for example, the displacement. The elastic modulus data is calculated by dividing the change in pressure by the change in strain. For example, assuming that the displacement measured by the displacement measuring unit 30 is L (X) and the pressure measured by the pressure measuring unit 46 is P (X), the strain ΔS (X) is a spatial differentiation of L (X). Therefore, it can be calculated using the equation ΔS (X) = ΔL (X) / ΔX. Further, the Young's modulus Ym (X) of the elastic modulus data is calculated by the equation Ym = (ΔP (X)) / ΔS (X). Since the Young's modulus Ym determines the elastic modulus of the living tissue corresponding to each point of the tomographic image, two-dimensional elastic image data can be obtained continuously. The Young's modulus is a ratio of a simple tensile stress applied to the object and a strain generated in parallel with the tension.

The elastic image construction unit 34 is configured to include a frame memory and an image processing unit, and secures elastic frame data output in time series from the elastic information calculation unit 32 in the frame memory. In contrast, image processing is performed.
The color scan converter 36 has a function of adding hue information to the elastic frame data from the elastic image construction unit 34. That is, the light is converted into the three primary colors of light, that is, red (R), green (G), and blue (B) based on the elastic frame data. For example, elastic data having a large strain is converted into a red code, and simultaneously elastic data having a small strain is converted into a blue code.

  The switching addition unit 24 according to the present invention includes a frame memory, an image processing unit, and an image selection unit. Here, the frame memory stores tomographic image data from the monochrome scan converter 32 and elastic image data from the color scan converter 36. The image processing unit combines the tomographic image data and the elasticity image data secured in the frame memory by changing the combining ratio. The luminance information and hue information of each pixel of the composite image is obtained by adding the information of the black and white tomographic image and the color elastic image at the composite ratio. Further, the image selection unit selects an image to be displayed on the image display 26 from the tomographic image data and elasticity image data in the frame memory and the composite image data of the image processing unit.

  The error evaluation unit 40 that evaluates the error of the elasticity image includes an RF signal frame data selection unit 28, a displacement measurement unit 30, an elasticity information calculation unit 32, an elasticity image configuration unit 34, a tomographic image configuration unit 20, and a monochrome scan converter 22. It is connected to the output of, and the error of the elasticity image is evaluated from the information of the tomographic image, the RF signal, the distortion, and the elastic modulus.

  The image control unit 44 is connected to the outputs of the error evaluation unit 40 and the interface unit 42. The image control unit 44 deletes a region evaluated as an error by the error evaluation unit 40 or a region designated by the interface unit 42, or adds error information. The interface unit 42 includes a keyboard, a trackball, and the like, and is linked to a cursor displayed on the image display 26.

  FIG. 2 shows a diagnostic procedure for elastic images of the prostate. First, an elastic image is acquired, and it is confirmed whether there is a hard region in the image region. If a hard region is recognized, an error determination is made as to whether or not the hard region is recognized as a positive elasticity diagnosis. In this error determination, a target tissue that does not need to be diagnosed even if it is actually hard, or a region that has been detected hard due to inappropriate measurement conditions for elasticity diagnosis, etc. is determined as an error. As such, it is distinguished so that it is not diagnosed, and attempts are made to avoid misdiagnosis. Note that a hard region that is finally recognized as not having an error is displayed without being removed from the image as being positive for elasticity.

  When it is determined that there is an error, it is classified into a case where it is inappropriate depending on the characteristics of the tissue and a case where the measurement condition is inappropriate. The case where it is inappropriate due to the characteristics of the tissue is, for example, a case where calcification, bladder, cyst, ureter, blood vessel, and anterior fibromuscular stroma (AFS) are displayed as an elastic image. Calcification, bladder, cysts, ureters, blood vessels, and prefibromuscular stroma (AFS) tissue are often displayed in blue because they are stiff or have fluid in the internal tissue. The case where the measurement condition is inappropriate is a case where an area affected by the shadow of calcification, an area that is not properly compressed, or an area where the cross section before and after the compression is shifted is displayed as an elastic image.

  Here, as shown in FIG. 2, an area including calcification is defined as error <1>. Since calcification is very hard, it is recognized hard in the elastic image and displayed in blue, but in the elastic image, it cannot be recognized whether the region displayed in blue is calcification. It should be noted that the calcification 50 region is a tissue that does not cause cancer and therefore does not require diagnosis.

  An area including the bladder, cyst, ureter, and blood vessel is defined as error <2>. The urinary bladder, cyst, ureter, and blood vessel all contain a low-echo fluid and are fluid, so they do not move together. Therefore, since distortion cannot be calculated accurately, the result is often calculated as a hard tissue. In addition, since these areas are tissues in which cancer does not occur, diagnosis is unnecessary.

  Also, let the AFS area be error <3>. As shown in FIG. 3 and the like, the AFS region 54 is a tissue region that is localized from the base portion of the prostate to the middle portion, and when observed in a transverse section of the prostate using a transrectal probe, the bladder 52 from the center of the prostate It is recognized as a low-echo area of an inverted triangle that spreads toward the capsule 56 on the prostate 53 side in front. Since the AFS region 54 is a tissue in which cancer does not occur, diagnosis is unnecessary.

  As shown in FIG. 4, a shadowing area 60 with insufficient echo behind the calcification 50 is defined as error <4>. The shadowing region 60 is a region where the echo signal is blocked by the calcification 50, and an echo signal reflecting the tissue cannot be obtained. Therefore, the calculation result of strain does not reflect the elasticity of the tissue, and as a result, it is often calculated as a hard tissue.

  In addition, an area that is not properly compressed is defined as error <5>. When the prostate 53 is compressed with a transrectal probe, the entire visual field range cannot be compressed equally by a single compression operation, and there is a direction in which sufficient compression cannot be performed. In many cases, a region that is not appropriately deformed by compression is calculated as a hard tissue. The error evaluation unit 40 determines that the region 62 is under-compressed when the distortion generated in the prostate skin part (fat, muscle) arranged outside the region of interest does not reach a predetermined threshold.

  In addition, an area where the cross section is shifted before and after the compression is defined as error <6>. Displacement information about where the measurement points moved after compression is acquired for each measurement point by correlation processing or block matching processing between RF signal frame data acquired before and after compression. If the surface deviates in the short axis direction of the ultrasound probe 12 during the time interval before and after the compression, the measurement surface before the compression and the measurement surface after the compression become different tissue surfaces. When the displacement search process is followed, it is unclear where it moved after compression. In such a case, displacement information becomes an error, and as a result, it is often calculated as a hard tissue. The error evaluation unit 40 determines whether or not the elastic image inside the region of interest has been imaged stably over time using the moving image.

Hereinafter, error evaluation and elasticity image processing will be described in detail.
As a first embodiment, a mode for manually evaluating and discriminating the above-described error region will be described with reference to FIGS. FIG. 3 is an image displayed on the image display 26. The image displayed on the left side is a tomographic image, and the image displayed on the right side is an image obtained by superimposing an elastic image on the tomographic image. These two images are images of the same cross section.

  The examiner confirms the region displayed in blue on the elastic image displayed on the right side of the image display 26 and displayed as the tissue is hard. Then, using the tomographic image displayed on the left side of the image display 26, it is determined whether this display is appropriate, that is, whether the area is an error area.

When an error area exists, the cursor unit 100 is moved by the interface unit 42 so that the error area can be recognized, and the area is designated on the elastic image. In this area, the start point of the area is determined by clicking a button on the interface unit 42, the range of the area is obtained by rotating the trackball, and the end point of the area is determined by clicking the button again. . When an area is designated on the tomographic image, the area is designated on the tomographic image constituted by the tomographic image construction unit 20 and the monochrome scan converter 22.
The image control unit 44 controls the elastic image forming unit 34 so that error information is displayed on the elastic image and the elastic image related to the region is deleted for the designated region.

  Then, the elastic image construction unit 34 performs error information image processing on the frame data of the frame memory of the elastic image construction unit 34 for the area instructed by the image control unit 44, and performs color scanning on the frame data subjected to the image processing. Output to the converter 36. Then, the image display 26 displays the image-processed elasticity image.

  This operation will be described with reference to FIG. The chart on the left side of FIG. 5 shows the operation procedure. The right image is an image displayed on the image display 26, and the upper image is an image in the state of S1, S2, and S3. The middle image is an image in the state of S4, and the lower image is an image in the states of S5 and S6.

(S1) First, the elastic image is frozen to display a still image. At this time, tomographic images at the same timing are also displayed in parallel.
(S2) The interface unit 42 is used to switch to the error area designation mode. The error <1> to <6> classification buttons are displayed on the right end of the image display 26 via the image control unit 44 as an error area designation UI. In the error area specification UI, error areas are colored according to the errors <1> to <6>.
(S3) Then, the tomographic image is viewed while the image is stationary. For example, if the region hard detected in the elastic image is an anterior fibromuscular stroma (AFS), it is recognized as error <3>. Click the error <3> button displayed on the error area specification UI to specify error <3> on the elasticity image or tomographic image. Even for other errors, the area is specified in the same manner.
(S4) The AFS region 54 on the elastic image or tomographic image is designated by the interface unit 42 while viewing the tomographic image.
(S5) The image control unit 44 detects the boundary (contour) of the region designated by the interface unit 42, and outputs information on the region to the elastic image construction unit 34.
(S6) The elastic image construction unit 34 removes the elastic image information of the error area detected by the image control unit 44, or performs the color classification classified by the error <3>, and the image processed image is converted into an image. This is displayed on the display 26.

  Next, as a second embodiment, a mode of semi-automatically evaluating and discriminating the above-described error area will be described with reference to FIGS. 1 to 4 and FIG.

As shown in FIG. 3, the examiner confirms an area displayed in blue that is displayed as a hard tissue on the elastic image displayed on the right side of the image display 26.
When a hard region exists, the cursor 100 is moved by the interface unit 42, and the region is designated on the tomographic image or the elastic image. At this time, the image control unit 44 evaluates the extent of the region using the region growing method. The region growing method is an image extraction method in which a reference point of a region to be extracted is set, and a pixel region whose luminance difference from the luminance of the reference point falls within a setting range is extracted.

  By clicking a button on the interface unit 42, a reference point is determined with the cursor 100 and a setting range is determined. Regions of pixels belonging to the set range are obtained by the region growing method. When the calcification 50 is extracted, a reference point is set by the interface unit 42 at the center of the calcification 50 displayed as a tomographic image or an elastic image. And since the calcification 50 displayed in the prostate 53 is a high-luminance area | region compared with the circumference | surroundings, the brightness | luminance range is set by the interface part 42 so that the luminance value 200 or more of a tomographic image is designated, for example. Then, the image control unit 44 specifies that the region having the luminance value of 200 or more is the region of calcification 50 by the region growing method.

  Further, the error evaluation unit 40 may designate an error region using “distortion”. The elastic image construction unit 32 that calculates the strain and elastic modulus of the biological tissue corresponding to each point on the tomographic image outputs the strain corresponding to each point to the error evaluation unit 40.

  When the calcification 50 is extracted, a reference point is set at the center of the calcification 50 by the interface unit 42. The image control unit 44 instructs the error evaluation unit 40 to calculate the distortion of the set reference point. The error evaluation unit 40 obtains the distortion of the reference point from the elasticity information calculation unit 32. Since the calcification 50 displayed in the prostate 53 has a smaller distortion than the surrounding area, for example, the distortion range is set by the interface unit 42 so that the vicinity of the reference point distortion is designated. Then, the error evaluation unit 40 designates the set distortion range area as the calcification 50 area.

As described above, the elastic image forming unit 34 is controlled so that the region designated by the image control unit 44 is displayed as error information in the elastic image or the elastic image related to the region is deleted.
Then, the elastic image construction unit 34 performs error information image processing on the frame data of the frame memory of the elastic image construction unit 34 for the area instructed by the image control unit 44, and performs color scanning on the frame data subjected to the image processing. Output to the converter 36. Then, the image display 26 displays the image-processed elasticity image.

  This operation will be described with reference to FIG. The chart on the left side of FIG. 6 shows the operation procedure. The right image is an image displayed on the image display 26, and the upper image is an image in the state of S11 and S12. The middle image is an image in the state of S13 to S15, and the lower image is an image in the state of S17.

(S11) is the same as (S1) above, and (S12) is the same as (S2) above, so the description is omitted here.
(S13) Click the area of the elastic image to specify the reference point. In the case of the region growing method, a luminance or hue range is set. When distortion is used to specify an area, a distortion range is set.
(S14) Then, the boundary of the region designated by the region growing method or distortion is detected on the elastic image.
(S15) The luminance distribution information of the ultrasonic tomographic image corresponding to the designated region is extracted using the region growing method.
(S16) The error evaluation unit 40 evaluates the extracted luminance information and automatically determines whether there is an error. If there is an error, the classification is determined. The automatic determination method will be described in the third embodiment.
(S17) The elastic image construction unit 34 removes the elastic image information of the error area detected by the image control unit 44, or performs the coloring classified by the error <3>, and the image processed image is converted into an image. This is displayed on the display 26.

Next, as a third embodiment, a mode for automatically evaluating and discriminating the above-described error area will be described with reference to FIGS.
In this embodiment, the error evaluation unit 40 automatically evaluates and discriminates the error region from the luminance information (display position and shape) of the tomographic image.

The error evaluation unit 40 performs error determination by evaluating threshold processing for luminance, shape information thereof, and position information. First, a low echo area is detected here. For example, Th (AFS) is set as a value indicating how many times it is based on the luminance average value, and the AFS luminance threshold is set.
(AFS brightness threshold) = Th (AFS) x Pmean
Set as. This Th (AFS) is 1 or less. Then, the error evaluation unit 40 performs determination based on the shape information. That is, it is determined whether the width tends to increase from the back side (near in the image) to the ventral side (deep part in the image). Further, the error evaluation unit 40 performs determination based on position information. It is determined whether the prostate is placed in the center without being biased to the right or left. Further, it is determined whether or not the bladder 52 is in the ventral region of the low echo area.

  Specifically demonstrating this embodiment, when observing the prostate region, from the transmitting / receiving surface side of the ultrasound probe, the prostate 53, the AFS region 54 adjacent to the prostate 53, the coating 56 covering the prostate 53 and the AFS region 54, The bladders 52 are displayed in this order on the outside of the AFS region 54 and the coating 56.

  The error evaluation unit 40 includes an image memory for storing the detected tomographic image data, a template memory for storing the tomographic image data of the pattern to be detected in advance, and the degree of coincidence between the image memory and the tomographic image data stored in the template memory. A calculation unit for detection and a position information analysis unit for recognizing the matching position are provided.

  An ultrasonic tomographic image of the prostate region is stored in advance in the template memory. Specifically, the template of the AFS region 54 is stored in the template memory in correspondence with the shape and positional relationship of the ultrasound probe, prostate 53, coating 56, and bladder 52. The luminance is bladder 52 <AFS region 54 <prostate 53 <coat 56, and this luminance information is also stored in the template memory.

  For example, in the case of the template of the AFS region 54, the distance between the ultrasonic probe and the AFS region 54, that is, the distance between the lower end portion of the image and the AFS region 54 is positioned as 2 cm. Further, an inverted triangular AFS region 54 adjacent to the fan-shaped prostate 53 is positioned. As described above, the template of the ultrasonic tomographic image of the AFS region 54 is stored in the template memory so as to correspond to the positional relationship of the other surrounding parts (the coating 56 and the bladder 52).

  The detected ultrasonic tomographic image data is taken in from the tomographic image construction unit 20 or the black and white scan converter 22, and the ultrasonic tomographic image is stored in the image memory. The calculation unit calculates the degree of coincidence between the ultrasonic tomogram stored in the image memory and the template of the ultrasonic tomogram stored in the template memory. This calculation is performed by binarizing according to the ultrasonic tomogram and the brightness of the template stored in advance. For example, based on the AFS luminance threshold, a portion with high luminance is set to “1”, and a portion with low luminance is set to “0”. For example, the prostate 53 and the capsule 56 are “1”, and the bladder 52 and the AFS region 54 are “0”. In this way, the template and the detected ultrasonic image data are binarized to calculate the degree of coincidence.

  The position information analysis unit recognizes a position and a region where the ultrasonic tomographic image data stored in the image memory matches the template. The image control unit 44 controls the elastic image constituting unit 34 so that error information is displayed on the elastic image or the elastic image related to the specified region is deleted.

Then, the elastic image construction unit 34 performs error information image processing on the frame data of the frame memory of the elastic image construction unit 34 for the area instructed by the image control unit 44, and performs color scanning on the frame data subjected to the image processing. Output to the converter 36. Then, the image display 26 displays the image-processed elasticity image.
In the above description, template matching is performed on the ultrasonic tomographic image. However, the error evaluation unit 40 performs template matching on the elastic image using the elastic image template and the elastic image output from the elastic image constructing unit 34. You may go.

  This operation will be described with reference to FIG. The chart on the left side of FIG. 7 represents the operation procedure. The right image is an image displayed on the image display 26, and the upper image is an image in the state of S21 and S22. The middle image is an image in the state of S23 to S24, and the lower image is an image in the state of S26.

(S21) is the same as (S1) above, and (S22) is the same as (S2) above, so the description is omitted here.
(S23) A region displayed as a hard region (blue) on the elastic image is automatically detected, and for example, hard regions are recognized as R1 and R2.
(S24) Then, the error evaluation unit 40 extracts the luminance distribution of the tomographic image corresponding to R1 and R2.
(S25) The error evaluation unit 40 detects the boundary (outline) of this region using the luminance information of R1 and R2, and specifies the error using the template matching described above. If there is an error, the classification is determined.
(S26) The image control unit 44 removes the elastic image information of R1 or performs the coloring classified by the error <3>. Further, the elastic image information of R2 is removed, or coloring classified by error <1> is performed. Then, the image processed image is displayed on the image display 26.

  Next, as another embodiment, a mode of automatically evaluating and discriminating the characteristics of each error described above will be described.

(Error <1>)
Calcification is generated by calcium deposition and is a very small and hard stone with a diameter of about 1mm. Therefore, when calcification is observed with ultrasonic waves, it is recognized as a very bright spot having a diameter of about 1 mm. Specifically, the error evaluation unit 40 determines that this area is calcification 50 based on the luminance information of the tomographic image in the area that is displayed in blue in the elastic image (the area that is locally high in the prostate). To do. The error evaluation unit 40 can recognize an image by performing threshold processing on luminance and evaluating the locality of the region. As the calculation of the average luminance value of the prostate image
(Average luminance value) = Pmean
Ask for. Then, the error evaluation unit 40 detects a region that exceeds the luminance threshold. For example, Th (Ca) is set as a value indicating a multiple of the luminance average value as a reference. And the calcification brightness threshold
(Calcification brightness threshold) = Th (Ca) x Pmean
Set as. Here, Th (Ca) is 1 or more. For each coordinate of the prostate image, the coordinates of the measurement point exceeding the luminance threshold are obtained, and a high luminance area as a group of those coordinates is detected.
Then, the error evaluation unit 40 determines whether or not the spread of the high luminance region is a circular region having a diameter of about 1 mm.
The image control unit 44 controls the elastic image configuration unit 34 to display the error <1> in the elastic image or delete the elastic image related to the specified region for the designated region.

(Error <2>)
The bladder, cyst, ureter, and blood vessel all contain fluid inside, and the behavior against compression shows a behavior specific to the fluid. That is, since it is not a living tissue, it tends to have displacement vectors of completely different sizes and directions between adjacent measurement points. In other words, since there is no connection to the internal tissues of the bladder, cyst, ureter, and blood vessel, the movement of each part is completely free, so that the variation in the magnitude and direction of the displacement appears remarkably. This behavior has been shown to be easily identified by assessing connectivity between tissues.
Therefore, the error evaluation unit 40 uses the signal output from the displacement measurement unit 30 to measure the variation in the magnitude and direction of the region displayed in blue in the elastic image or the statistical feature amount thereof, and this elasticity The image area is determined as error <2>. This measurement is disclosed in Patent Document 2.

Specifically, the error evaluation unit 40 obtains a two-dimensional displacement vector (Xi, j, Yi, j) at each measurement point. Then, the element data group calculation of the image vertical axis direction (y direction) component and the image horizontal axis direction (x direction) component is performed, and the variation in displacement and direction or its statistical feature value is obtained. If variations in the magnitude and direction of displacement appear significantly in the measured area, the area is defined as, for example, the bladder 52. In particular, since the bladder is a wide low-echo region located on the ventral side, it can be determined by further considering the position information of the part. Note that the error evaluation unit 40 may determine that the bladder, cyst, ureter, and blood vessel have a low correlation coefficient.
Then, the image control unit 44 controls the elastic image configuration unit 34 to display the error <2> in the elastic image or delete the elastic image related to the specified region. Do.

(Error <4>)
As shown in FIG. 4, when the calcification 50 is detected in the determination of the error <1>, the error evaluation unit 40 determines whether the rear region 60 has sufficient luminance information compared to other regions. judge.
First, as described above, error <1> is detected. Then, the error evaluation unit 40 sets the rear coordinate area as the calcification rear area, and determines whether or not the average luminance has sufficient luminance to perform the calculation. For example, with the brightness average value of the entire prostate as a reference, Th (Shadow) is set as a value indicating the multiple of the brightness value, and the shadowing brightness threshold is set.
(Shadowing brightness threshold) = Th (Shadow) x Pmean
And set. Here, Th (Shadow) is 1 or less. And
(Luminance average of calcification rear area) <(shadowing luminance threshold)
If so, the error evaluation unit 40 recognizes it as the shadowing area 60.
Then, the image control unit 44 controls the elastic image configuration unit 34 to display the error <4> in the elastic image or delete the elastic image related to the specified region. Do.

(Error <5>)
As shown in FIG. 8 (a), when the prostate is compressed with a transrectal probe, the entire visual field range cannot be compressed equally by a single compression operation, and a region 80 that cannot be compressed sufficiently is generated. The error evaluation unit 40 is appropriately compressed in the direction by determining whether or not the distortion generated in the prostatic membrane portion 56 (fat, muscle) arranged on the ventral side of the region of interest exceeds a predetermined threshold. Determine whether or not.
The film part 56 has a higher brightness than the glandular tissue region of the prostate, and the film part 56 is characterized by being continuously connected as an arc-shaped band. It is possible to automatically detect the region of the film part (contour part).
Then, the image control unit 44 deletes and displays the elastic image in the direction not exceeding the threshold value.

As shown in FIG. 8B, the image control unit 44 displays an error <5> on the elastic image or deletes the elastic image related to the uncompressed fan-shaped region 82. In addition, the elastic image forming unit 34 is controlled.
Furthermore, the image control unit 44 removes the elasticity image behind the skin part 56 from the elasticity image in the direction exceeding the threshold value, and extracts and displays only the elasticity image of the prostate tissue part 53 inside the skin part 56. It may be processed as follows.

(Error <6>)
When the measurement cross section is shifted before and after the compression and the tissue regions are different, for example, the error evaluation unit 40 counts an extremely small value for a parameter such as a correlation coefficient indicating the degree of matching when calculating the displacement. That is, it can be determined by setting a threshold for the value of the correlation coefficient. This correlation coefficient threshold is set as Cthrs.
Then, for each coordinate of the prostate image, the coordinates of the measurement points that do not exceed the correlation coefficient threshold are obtained, and the low correlation count region as a group of these coordinates is detected.
Then, the image control unit 44 controls the elastic image configuration unit 34 to display the error <6> in the elastic image or delete the elastic image related to the region for this region.

(Coating part)
The compression determination distortion threshold value εthrs for determining the degree of compression is set as the distortion value. It is assumed that this distortion threshold is a threshold for distortion values normalized by the distortion average value εmean measured at the distortion values at all measurement points in the prostate image. Normalize the strain distribution of the prostate. That is, the strain value εmeas (i, j) measured at each measurement point is divided by the strain average value εmean measured at all measurement points. That means
εmean = Σεmeas (i, j) / NN: Total number of measurement points εnorm (i, j) = εmeas (i, j) / εmean
Set as. In this way, it is possible to set a compression determination distortion threshold that does not depend on the amount of compression before and after compression. The error evaluation unit 40 determines whether or not the compression determination distortion threshold is exceeded with respect to the normalized distortion value εnorm (i, j) measured in the prostate capsule. If it exceeds, it is determined that the compression in the direction of the film portion coordinates (i, j) was appropriate. Although the above method has been described using the strain distribution, if a strain image is constructed, a threshold value corresponding to the compression determination strain threshold value is assigned to the luminance information and hue information of the strain image to determine whether compression is appropriate. It may be like this.

  Further, a frame that has cleared the measurement condition of the above evaluation criteria with the highest result is selected from the elastic image moving image and applied as a diagnostic image. As described above, it is possible to recognize errors (errors <5> and <6>) caused by an inappropriate compression operation by calculation. By using this method, it is possible to select a frame at the moment obtained by the most appropriate compression operation from a series of frames of a moving image. An example of the method is shown in FIG.

(S51) First, the error evaluation unit 40 automatically detects an error (error <5>, <6>) generated by an inappropriate compression operation technique on the apparatus.
(S52) For each frame, the total area of the error regions (hereinafter referred to as the total error area) is calculated.
(S53) The frame having the smallest total error area is detected from among a plurality of frames of the moving image.
(S54) The image control unit 44 selects the image to be applied to the diagnosis as being the still image at the moment when the procedure is most appropriate, and displays it on the image display 26.

  Also, for example, the condition that the total error area due to errors <5> and <6> is 10% or less of the total area is imposed, and only the frame that clears this condition (hereinafter referred to as error total area condition) displays the elastic image on the device. May be displayed. Further, the persistence processing (time direction frame addition processing) may be performed only between frames that have cleared the total error area condition.

In the above description, the tomographic image and the elastic image are displayed side by side in parallel. However, when an error is determined semi-automatically or automatically, only the elastic image may be displayed.
Needless to say, it is not limited to the subject of the prostate, and it is needless to say that how the error is determined and reflected in the image is the same even if the target tissue is changed.
In the above embodiment, identification of the tissue part by B-mode image was attempted, but by combining with RVS (real-time virtual sonography), for example, it becomes possible to use 3D image information such as CT and MRI, For example, tissue identification such as bladder and AFS is easily performed. The RVS is an ultrasonic diagnostic apparatus disclosed in Japanese Patent Laid-Open No. 10-151131.

The figure for demonstrating the whole structure of this invention. The figure for demonstrating the various errors of this invention. The figure for demonstrating the display form of this invention. The figure for demonstrating the display form of this invention. The figure for demonstrating the 1st Embodiment of this invention. The figure for demonstrating the 2nd Embodiment of this invention. The figure for demonstrating the 3rd Embodiment of this invention. The figure for demonstrating other embodiment of this invention. The figure for demonstrating other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus, 10 Subject, 12 Ultrasonic probe, 14 Transmission part, 16 Reception part, 17 Transmission / reception control part, 18 Phased addition part, 20 Tomographic image structure part, 22 Black-and-white scan converter, 26 Image display 28 RF signal frame data selection unit, 30 displacement measurement unit, 32 elasticity information calculation unit, 34 elasticity image configuration unit, 36 color scan converter, 24 switching addition unit, 40 error evaluation unit, 42 interface unit, 44 image control unit

Claims (12)

An ultrasonic probe, tomographic image constructing means for generating a tomographic image based on RF signal frame data of a tomographic region of the subject via the ultrasonic probe, and the tomographic image based on the RF signal frame data Elastic information calculating means for obtaining strain or elastic modulus of tissue in the site; elastic image constructing means for generating an elastic image in the tomographic site based on the strain or elastic modulus obtained by the elastic information calculating means; And / or an ultrasonic diagnostic apparatus comprising display means for displaying the elastic image,
Using the luminance information of the elastic image and the tomographic image, an error evaluation unit that evaluates an error of the elastic image and designates an error region, and error information in the elastic image for the region specified by the error evaluation unit And an image control means for deleting the elastic image relating to the error region.   The ultrasonic diagnostic apparatus according to claim 1, further comprising an interface unit to which information for designating the error image or the error region of the tomographic image is input.   The error evaluation unit extracts a pixel region belonging to a predetermined setting range using luminance information of the elasticity image and the tomographic image, and designates the error region. Ultrasonic diagnostic equipment.   The ultrasonic diagnostic apparatus according to claim 1, wherein the error evaluation unit designates the error region based on a display position and a shape of a predetermined part displayed in the elasticity image or the tomographic image.   The error evaluation unit includes an image memory for storing the detected tomographic image data, a template memory for storing in advance the tomographic image data of the pattern to be detected, and the degree of coincidence between the image memory and the tomographic image data stored in the template memory The ultrasonic diagnostic apparatus according to claim 1, further comprising: a calculation unit that detects the position and a position information analysis unit for recognizing the matching position.   2. The ultrasonic diagnosis according to claim 1, wherein the error evaluation unit designates the error region by evaluating a threshold value processing for luminance of the elasticity image or the tomographic image and a locality of the region. apparatus.   The ultrasonic diagnostic apparatus according to claim 1, wherein the error evaluation unit specifies the error region by specifying variations in displacement magnitude and direction based on the plurality of RF signal frame data.   The error evaluation unit sets a coordinate area behind a predetermined error part, and determines whether the average luminance of the tomographic image has a luminance sufficient for performing an elastic calculation. Ultrasound diagnostic equipment.   The ultrasonic diagnostic apparatus according to claim 1, wherein the error evaluation unit designates the error region based on the distortion.   The ultrasonic diagnostic apparatus according to claim 1, wherein the error evaluation unit designates the error region based on a correlation coefficient indicating a degree of matching in calculating displacement.   The ultrasonic diagnostic apparatus according to claim 1, wherein the error evaluation unit selects a frame satisfying the measurement condition of the evaluation criterion from the moving image of the elasticity image, and performs evaluation based on the selected frame. .   2. The method according to claim 1, wherein the error evaluation unit designates the region as the error region when the distortion generated in the region arranged outside the predetermined region of interest does not reach a predetermined threshold value. Ultrasonic diagnostic equipment.

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